Internal combustion engine



March 29, 1932. w R. @msm/OLDY 1,851,669

INTERNAL COMBUSTION ENGINE Filed Feb. 27, 1928 E E. E atto/:Mau

Patented Mar. 29, 1932 UNITED s'mrasv larnaNr oli-Fica n WALTER 1R. GRISWOLD, OF DETROIT, MICHIGAN, ASSIGNOR TO PACKARD MOTOR CAB t COMPANY,I OF DETROIT, MICHIGAN, A CORPORATION OF lMICHIGAN INTERNAL coitBUsrIoN ENGiNE Application led February 27,` 1928. Serial No. 257,231.

This invention relates to internal combustion engines and more particularly to the neutralizing or balancing of certain free inertia forces which act on the crank'shafts of 5 such engines. It contemplates a method of balancing or canceling ot such forces by opposing them with the proper components of other. inertiaforces derived from a separate balancing system,"the`other components of such balancer forces being independently bal-I anced, or otherwise eliminated.

The invention is particularly applicable to engines having four-throw crank shafts, such as the well known four-cylinder automobile engine, in which all of the cranks are arranged in a common plane longitudinally of the shaft, and in which the unbalanced forces act in the vertical plane through the shaft axis. It has been ldisclosed in connection with such an engine, but it is to be understood that the invention is not so, limited, but may be applied to any engine -in which free or unbalanced inertia forces act on the crank shaft.

It iswell known that much of the roughness in certain types of engines is vcaused by the secondary inertia forces, which are second order harmonic components of the total inertia force and which do not cancel out but have a definite resultant, causing an appreciable .reaction on the engine supports. It has been proposed'to neutralize these secondary inertia force by rotary balancing devices` and also by reciprocating or oscillating balance weights driven from the engine crank shaft through ltoggle linkages of various kinds, which provide two vibrations of the weights for each revolution of the shaft. The undesirable high speed gearing required by provide an improved method of balancing the inertia forces actmg'on an engine shaft.

Another object of the invention is to provide an internal combustlon engine with a simple and compact balancing system or derotary balancing devicesv is avoided in such One of the objects of this invention is to vmovement multiplying means.

.Another object of the invention is to provide a balancer for engine crank shafts having a pair of inertia members so disposed aS.

to balance the secondary inertia forces of the crank shaft when d riven directl from the n crank shaft without toggles or ot er complicated linkages. A

Another object of the invention is to provide engine balancing means in which the inertia 'members are constrained to movement in a fixed path without heavy reactions on the guiding and supporting means.

Another object of the invention is to rovide such balancing means which shall have no highly stressed members, shall not occup excessive space in the engine crank case, an which shall be inexpensive to build and maintam. l

Other objects of the invention will appear from the following description taken in con nection with the drawings, which form a part of this specification, and in which Fig. 1 is a transverse sectional view through an internal combustion engine having ba-lanc` ing means embodying this invention;

Fig. 2 is a detail view, partially in section substantially on the line 2-2 of Fig. 1;

' Fig. 3 is a view in side elevation, partially broken away and partially in section, and to a somewhat smaller scale, of a part of the engine shown in Fig. 1, and

Fig. is a transverse sectional view show-` ing a modified form of the invention.

Referring .to the drawings, at 10 is shown an internal combustion engine having a crank case 11 provided with a lowerclosure forming an Aoil panA 12. The crank ycase is provided with transverse webs such as 13, in which are mounted bearings 14 for the engine crank shaft 15, which in the embodiment illustrated is of the well known four-throw type. Each ofthe cranks 16 of the crank shaft.v 15 is con- 100 passages (not shown) which are connected to combustion spaces 24 in the head 22 by ports cured upon the'crank case 11 and provided with a removable cylinder head 22. The cylinder block' 21 is also provided with the usual intake passages 23, and with similar exhaust 25. These intake and exhaust ports 'are each controlled by a valve, such as 26, which may be of the well known poppet type, slidably mounted in a guide'27 and vurged toward its closed position bya suitable valve spring 28 in the Well known manner. These valves may be actuated lthrough valve followers 29 and rocker arms 30 from cams 31 on an engine camshaft 32, driven in timed relation tothe ycrank shaftl in any suitable manner.

The cylinder block and head are also preferably formed with cooling passages 33 for the circulation of a cooling medium, and the head is provided with suitable ignition apv paratus such as the spark plugs 34.

' 'The balancing means of this invention is preferably mounted within the crank case 11 near the middle thereof. As shown in Fig. l, the mounting is a lug 36, integral withthe crank case wall, on which the weight or inertia members 37 are pivotally supported. The lug is arranged adjacent 4to and may be integral with the web 13 of the center shaft hearing 14, so that the weight members may operate substantially in the transverse plane of the bearing without interference with the cranks.

Each of the weight or inertia members 37 is provided with a radius arm 38 which may be integral therewith ory rigidly attached thereto, and which is pivoted at the other end for oscillatory movement about a common point on the lug 36, which is the center of oscillation of the weight members.v The center may be conveniently formed by a pin or stud 39, screwed into the lug 36, and cooperating with a tuitable eye 41 in the end of the arm 38. In this way the weight members are restrained by the arms to movement in short cir- Y: cular arcs about the pin 39.

`The weight members are driven from and in synchronism-with the crank shaft 15, to which `they are directlyconnected. For this purpose 'the crank shaft is formed with an eccentric 42,

- preferably integral therewith, which is located adjacent the center main bearing 14.

, This eccentric is arranged in a definite anguvso lar or phase relation to the .crank shaft, and in the embodiment shown is disposed at 90 to the plane of the cranks 16, as clearly shown in Fig. 1. I Side by side on this eccentric are mounted a pair of eccentric followers or straps 43, each comprising a rod portion 44 and a cap portlon 46 removably secured to the rod portion in the well known manner. Integral bers 37, which connection may be conveniently effected by a pin 49, threaded into the side of the weight member 37, and having a nut 51 by which the eye 48 is retained on the pin.

It will be understood that the eccentric rods are disposed at an angle of 90, one being connectedvto the upper and the other to the lower weight member. By reason of the direct con nection afforded by these rods, the weight members l37 are oscillated through shortarcs determined by the arms 3 8, and in synchronism with the crank shaft, that is each of the Weights makes one complete oscillation for each revolution of the crank shaft.

In order 'to relieve the pin 39 and its supporting lug of large reaction stresses, and to reduce the necessary mass of the weight members, the pin 49 is preferably arranged on an axis passing through the center of percussion of the member with respect to the pivot 39, which center, in the particular embodiment illustrated, lies close to the center of gravity of the weight member. By this arrangement the reaction forces at the pin 39 are very small, being limited to the radial acceleration of the weight member caused by its arcuate movement. As the length of the arc of travel is short compared with its radius the radial component of this motion is practically negligible, and the path of travel may be considered as a straight line. By this construction also, the inertia forces of the weight members 37 are directly transmitted to the eccentric rod 47, so that the necessary balancing pressure is secured by a much smaller weight than would otherwise be the case.

The total inertia, forces of the balancing system are therefore exerted on the crank shaft 15 through the rods 47 and the eccentric 42, and. these forces are periodic and in synchronism with the engine forces. yThey may be resolved into primary and secondary components, the primary component being a constant, while the secondary component is a harmonic variable and out of phase with the shaft forces by reason of the disposition of the'eccentric 42 on the shaft.

In the applicants method of balancing, the unbalanced shaft forces are directly neutralized by the similar component of the balancing forces, vwhich is the secondary component, and as these are of the same frequency it is not necessary to double the frequency of the balancing system. Instead, the constant primary force is independently eliminated, and by a proper angular disposition the secondary forces are caused to balance f tion, the primary force component exerted i by the weight members-37, takes the form of a rotat' vector lof constant magnitude, and this mayI y readily eliminated by simlple rotary ba ance weights 52. These weig ts are conveniently secured to the crank cheeksad jacent the center bearing 14 in any desired manner, and rotate with the crank shaft to neutralize or 4balance out the primary force mentioned. ASuitable compensation for the static unbalance of the crank shaft, by reason l0 of the oif center mass of the eccentric 42, may be conveniently combined vin these rotary weights52, since this unbalance is also a rotary forcej which may be readily combined with the primary inertia force into a constant 15 resultant.

The secondary componentv may be further resolved into cpmponent forces acting parallel and normal to the plane of action of the l, engine forces. In the embodiment ofthe invention herein described these components are horizontal and vertical. By reason of the angular relationship chosen between the eccentric rods andthe plane of action of the.

forces, the horizontal components cancel out when transferred to this plane of action, leaving the vertical component acting on 'the unbalanced engine forces in opposite phase relation, whereby these unbalanced engine forces are neutralized.

In Fig. 4is illustrated a modified form of the construction shown in Figs. 1 to 3. In

this embodiment of the invention the weight members 57 are preferably cylindrical in form and are mounted to reciprocate in cylindrical 'guides"58, which may be formed mtegrally with the crank case 1,1. The axes of these cylindrical guides are disposed substantially' at right angles to and above and below the horizontal pla-ne of the crank shaft, and the 40 weight members 57 are reci roc'ated therein directly from the crank sha 15 through the eccentric 42, the eccentric follower and the eccentric rod 47, as in the form of the invention previously described. In this form of to the weight members 57 by pins 59, which are located as nearly as practicable atzthe cen-y -gmes wherein the forces causing theunbalance are opposed by other forces similar in y kind and in order, suchextraneous forces as are incident to the balancing force being 5 separately eliminated. In this way a simple the device theeccentric rods 47 are connected ythe cylindrical ,guides 58 are relieved of mostv vides an improved method of balancing en-y balancing'y system,`v operable at engine speed,

.is made possible.

'ter of percussion, large reaction stresses are removed from the supporting lug, 'the crank case, and other parts of the engine.

It will be understood that various forms of the, invention other than those described above may be used without departing from the spirit or sco e of the invention.

'Having thus l eseribed the inventiomrwliat is claimed and desired to be secured by Letters Patent, is: l 1. The method of balancing the secondary inertia forces of an engine crank shaft which consists in opposing the said inertia forces by the combined forces of a balancin system, and simultaneously and indepen ently balancing the constant primary force of said balancing (system.

2. The method of balancing the secondary inertia. forces of an engine crank shaft which consists in driving a separate lbalancing* system from said shaft, imposing on the shaft the inertia forces of said balancing system in opposite phase relation, and independently balancing the constant component of said imposed forces. v

. 3. The method of balancing the secondary inertia forces of an engine crank shaft, which consists in imposing on said crank shaft both the variable and the constant force compoi nents of an extraneous balancing force in opposite phase relation to said engine forces,

and removing said constant component by separately counterweighting the crank shaft.

4. ,The combination with an internal coinbustion engine having a crank shaft, of a pair of inertia members pivotally4 mounted to oscillate about fixed centers on the engine, a driving vmember on the crank shaft 115.

in predetermined angular relation thereto, and means connectingy the driving member with each of said inertia members at the center of percussion thereof referred to its center f oscillation.

'5.'The combination of an internal com bustion engine yhaving a crank case and a crank shaft journaled therein, ofa balancing device comprising a weight member havv ing an integral arm pivotally secured to the crank case, an eccentric integral with the crank shaft adjacent a journal lbearing thereof, and an eccentric rod operable by the eccentric and ivotally connected to the weight member at t e center of percussion thereof. j

l6/The combination of an internal combustion en 'ne having a crank case and a rank sha t journaled therein, ,a pair of weight membersmovably mounted on the crank case, an eccentric on the crank shaft having a definite angular position thereon,

and a pair of eccentric straps on the eccentric, each connected to one of the weight members to move said members in a definite phise relation.`

bustion engine having a crank shaft with cranks arranged in a common plane, of an eccentric on said shaft disposedl at right angies to said crank p1ane,a pair of'mer'tia members mounted to oscillate on the engine in paths symmetrical to and on opposite sides of the horizontal plane rvof thelshaft, and

means to actuate said inertia members from said eccentric and in synchronism therewith. 8. A balancing device for the secondary inertia forces of an internal combustion enf gine having a crank shaft, comprisin v1nertia members movably mounted'on sai en'- Y s gine, means'directly connectingthe inertia members to the crank shaft in a predetermined phase relation for movement 'at the I v same rate, whereby part of the inertia forces of the inertia members balance the secondary inertia forces of the engine, and means on said crank shaft to balance the yremainder of the forces of said inertia members.-

9. A balancing device for the inertia forces of an engine crank shaft comprising movable inertia members, an `eccentric on the shaft to drive said inertia members and a balance weight on the shaft to balance said eccentric and a portion of the -force of said inertia members.

10. The combination with an internal comybustion engine of which the secondary inertia forces act in the verticaLplane of the crank shaft, of a balancing device for sadA forces comprising inertia masses mounted for movement in paths symmetrical to the horizontal plane of .the crank shaft, an eccentric on said crank shaft, and eccentric straps connect-ing each inertia mass tosaid eccentric by rods disposed substantially at ri ht angles to each other.

n testimony whereof I- aix WALTER R. GRISWOLD.

The combination with an internal comniy signature., 

